The present invention relates to a system for selectively performing sludge extraction from a concentrator in a sludge bed settling apparatus, and also for selectively performing washing of the concentrator and the interior of the sludge bed settling apparatus.
It is known that in the treatment of used or raw water in a sludge bed type settling apparatus, a portion of the sludge resulting from such treatment must be periodically extracted from the settling apparatus. It is further known to achieve such sludge extraction by using a system of pipes provided with manually or pneumatically operated diaphragm valves, possibly connected to an automatic control and adjustment system.
However, the use of such diaphragm valves inherently involves certain inconveniences, one of which is the necessity of maintaining the value of fluid pressures employed within the system within narrow limits to avoid bursting of the diaphgrams. A further inconvenience is the need for providing a separate fluid supply to each diaphragm valve. An even further inconvenience in such known systems is the inherent risk of draining the decanting or settling apparatus when the extraction is stopped. An additional drawback of such known systems is the high cost of diaphragm valves.
The use of vacuum primed siphons to achieve sludge extraction would eliminate certain of the above disadvantages inherent in the use of diaphgram valves. However, the provision of a separate vacuum system would involve considerable extra expense.
Additionally, it is known that when a plate type settling apparatus operating according to the activated sludge bed principle is used for the water treatment operation, it is routinely necessary to wash the interior of such apparatus. Such washing operation normally must be manually carried out, and it is extremely difficult to achieve such manual washing in the area of the apparatus beneath the plates.